I just had an old Mercedes hand install a Pertronix II electronic ignition in my 1972 4.5 D Jetronic. I have had cold start roughness for some time and hoped this would help.
It didn't. Let me add that I know its not the AAV valve as it has been restored with a new thermal element and tested. What other part should I be looking at?
Incidentally, I have used a Pertronix I on my old Rolls Royce I6 with great success, with a noticeable improvement in quick starting and general performance. Is there any reason to think that the original Pertronix I system is actually better than the more "advanced" system II?

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Berfinroy in CT
Present vehicles:
1973 300 SEL 4.5
1959 Rolls Royce Silver Cloud I
1973 Citroen DS23 EI five speed
Past vehicles;
1959 Thunderbird convertible/430
1958 Bentley S 1
1976 ex-Max Hoffman 6.9
1970 300SEL 2.8
1958 Jaguar MK IX
1961 Jaguar MK IX
1963 Jaguar E-type factory special roadster
1948 Plymouth woody
1955 Morgan plus 4
1966 Shelby GT350H Mustang